The present invention relates in general to equalizing and amplifying and more particularly concerns novel apparatus and techniques for providing stereo power amplification especially useful for an automobile at high power levels with relatively low cost through novel circuitry techniques including novel dynamic equalization that alters the equalization characteristic in those frequency ranges where a present signal spectral component may cause overloading while maintaining the equalization in other frequency ranges.
It is common practice to energize stereo power amplifiers in an automobile directly from the 12-volt D.C. supply. To prevent D.C. from biasing the loudspeaker diaphragms offcenter, these amplifiers typically require a costly large capacitance connected between each power amplifier channel and a respective loudspeaker. And if equalization is used, the amplifier may be overloaded when receiving a spectral component that is appreciably boosted by the equalization circuit, thereby producing undesirable audible distortion or limiting the sound power output of the system.
Accordingly, it is an important object of this invention to provide improved amplifying and/or equalization.
It is another object of the invention to achieve one or more of the preceding objects while increasing the ratio of power output without audible distortion to cost.
It is a further object of the invention to achieve one or more of the preceding objects while providing equalization.
It is still a further object of the invention to achieve one or more of the preceding objects while reducing capacitor bulk and cost.
It is a further object of the invention to achieve one or more of the preceding objects with dynamic equalization that maintains a desired equalization contour except in those portions of the frequency range where spectral components then being amplified would produce audible overloading.